<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>媒体查询1</title>
    <style>
        body {
            background-color:lightgreen;
        }

        @media (width: 300px){
            body {
                background-color:black;
            }
        }

        /* @media (min-width: 300px){
            body {
                background-color:black;
            }
        }

        @media (min-width: 600px){
            body {
                background-color:blueviolet;
            }
        }

        @media (min-width: 900px){
            body {
                background-color:burlywood;
            }
        } */
    </style>
</head>

<body>


</body>

</html>